The purpose of this paper is to demonstrate how Bertrand Russell depicts the relation of mysticism to three other areas of human activity: philosophy, science, and religion, and thus: its special role. In his essay Mysticism and Logic (1914), Russell defines mystical thinking as beliefs in (1) the existence of special insight, (2) the unity of all things, (3) the unreality of time, and (4) the effacement of the boundaries between good and evil. Although he considers full mysticism – as a belief about the ontic structure of the world – to be erroneous – as a life attitude he attributes to it an element of wisdom that is lacking in other areas of human intellectual activity. Mysticism proves wrong also at the epistemological level, i.e. as a certain test of truth. But in its spirit of inquiry, it contains something that science also benefits from, and from which, therefore, scientific philosophy should take its cue. What additionally gives mysticism its value is the claim of impartial contemplation which gives rise to an attitude of love towards the whole world. Significantly, it was the combination of the best features of mystical thinking with scientific thinking and method which gave rise to Russell’s advocacy of scientific philosophy. In light of this, I argue that according to Russell mysticism is not an exclusively religious phenomenon, which is demonstrated, among other things, by the fact that he attributes two aspects of mysticism to the field of mathematics.